This PET scan shows us that once addicted to a drug like cocaine, the brain is affected for a long, long time. In other words, once addicted, the brain is literally changed. Let’s see how...

In this image, the level of brain function is indicated in yellow. The top row shows a normal-functioning brain without drugs. You can see a lot of brain activity. In other words, there is a lot of yellow color.

The middle row shows a cocaine addict’s brain after 10 days without any cocaine use at all. What is happening here? [Pause for response.]Less yellow means less normal activity occurring in the brain - even after the cocaine abuser has abstained from the drug for 10 days.

The third row shows the same addict’s brain after 100 days without any cocaine. We can see a little more yellow, so there is some improvement - more brain activity - at this point. But the addict’s brain is still not back to a normal level of functioning... more than 3 months later. Scientists are concerned that there may be areas in the brain that never fully recover from drug abuse and addiction.